docs: def pdf_to_img(pdf_file, page_num, page_width, page_height):
      """
      Converts pdf file into image
      :param pdf_file: path to the pdf file
      :param page_num: page number to convert (index starting at 1)
      :return: wand image object
      """
      img = Image(filename="{}[{}]".format(pdf_file, page_num - 1))
      img.resize(page_width, page_height)
      return img